I used the same instructions (from droidrzr.com) and had no problems at all. Just make sure you're stock 173 with nothing frozen or altered and follow the directions as stated. I didn't even need the extra step to retain root as it survived the update on its own using Voodoo.
Good luck and enjoy ICS.

There are two files. The .zip is the update which is 458mb and a .crc which is only 10 bytes. The file took almost an hour to download on my phone. Once on the phone copy both to /cache and follow the instructions (using ES File Explorer) as posted at droidrzr.

Yes but it's a torrent so you'll need the appropriate app whether your downloading straight to your phone or to a computer and transferring to your phone. I got TTorrent from the market (free) to download it. On the phone, you will click the link and save it to your phone (it's like 19kb) then open your torrent app and find where you saved the link and your download will begin. The screen shot in my previous post shows where the actual download was saved on my phone.
I'm not real big with torrents but this one was pretty straight forward.

Yes but it's a torrent so you'll need the appropriate app whether your downloading straight to your phone or to a computer and transferring to your phone. I got TTorrent from the market (free) to download it. On the phone, you will click the link and save it to your phone (it's like 19kb) then open your torrent app and find where you saved the link and your download will begin. The screen shot in my previous post shows where the actual download was saved on my phone.
I'm not real big with torrents but this one was pretty straight forward.

Go to the downloaded folder at /sdcard/torrent/OTA.ICS.Build.6.14.75.XT912 and that's where the two file are that need to be copied into system/cache. There are detailed instructions at the link Smalltowngirl posted above and also on droidrzr.com.
It's also wise to read through the entire threads to help avoid some of the problems others are experiencing. I followed the instructions exactly as posted and used the apps (ES File Explorer and Rom Manager) recommended by the OP. I was also already rooted and kept root through the update using Voodoo OTA Rootkeeper.
This is not to be taken lightly. If you don't understand what the directions are meaning, either read more about it or hold off until someone simplifies the procedure (which probably won't be long).
Good luck.

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